Fuel cells are electrochemical cells that produce usable electricity by the catalyzed combination of a fuel such as hydrogen and an oxidant such as oxygen. In contrast to conventional power plants, such as internal combustion generators, fuel cells do not utilize combustion. As such, fuel cells produce little hazardous effluents. Fuel cells convert hydrogen fuel and oxygen directly into electricity, and can be operated at higher efficiencies compared to internal combustion generators.
A fuel cell such as a proton exchange membrane (PEM) fuel cell typically contains a membrane electrode assembly, which consists of a catalyst coated membrane disposed between a pair of gas diffusion layers. The catalyst coated membrane itself typically includes an electrolyte membrane disposed between a pair of catalyst layers. The respective sides of the electrolyte membrane are referred to as an anode portion and a cathode portion. In a typical PEM fuel cell, hydrogen fuel is introduced into the anode portion, where the hydrogen reacts and separates into protons and electrons. The electrolyte membrane transports the protons to the cathode portion, but prevents the passage of electrons. This allows a current of electrons to flow through an external circuit to the cathode portion to provide power. Oxygen is introduced into the cathode portion and reacts with the protons and electrons to form water and heat.